About 9 a.m., the highway workers were riding in the truck near 140th Street retrieving orange safety cones that had been set out earlier for a bridge project that had been canceled because of snow squalls in the area, IDOT spokesman Mike Claffey said.

One IDOT worker was on the truck's rear platform picking up the cones and handing them up to another, while a third was driving, he said.

The southbound van, which belonged to Parliament Builders, a Chicago contracting company, veered from the center lane of the expressway (Interstate Highway 94), hit the IDOT truck from behind and pushed it into a concrete median barrier, state police said.

Precipitation was falling at the time of the accident, and weather may have played a role in the crash, Claffey said.

Porter was cited with a failure to yield to an emergency vehicle and illegal lane usage, state police said.

The highway workers were taken to local hospitals with injuries that were not believed to be life-threatening, Claffey said.

Porter, meanwhile, was pinned inside the vehicle, and Calumet City Fire Department emergency personnel worked about 20 minutes to pull him out before flying him in critical condition by medical evacuation helicopter to Advocate Christ Medical Center.

A passenger in Porter's van was treated for minor injuries at a hospital, state police said.